Optimizing for both stiffener and frame spacing

[HyperSizer User]

Consider we have a typical semi-monocoque pressurized tube with both stiffener running longitudinally and frames (or rings) perpendicular to the axis of cylinder with different loading scenarios. Say, we want to decide on the optimal distance between the adjacent stiffeners and adjacent frames. For the stiffeners, since they are part of the concept that we choose in HyperSizer, we can directly specify a range for the distance between the stiffeners as one of the variables and HyperSizer gives us the optimal value. But for the rings, I assume we need to build several FE models with different frame distances, optimize each FE model and then compared the weight among the resulted optimal concepts. Is there any more efficient approach?

[Phil]

The thing that is most likely going to dictate the beam spacing will be buckling length, so in these kind of cases, what we will typically do is start with one FEA, then manually iterate on a buckling length to find the optimum, by just typing new buckling lengths on the buckling tab.  Then when settled on a new buckling length, go back and update the frames in the FEM.  That saves a lot of extra modeling time and the manual iterations will get you in the ball park.  You can also get in the ball park with this sort of thing using automation with the HyperSizer Object model.  See the White paper:
http://hypersizer.com/support/dload/wp01_using_object_model.php